Sewing machine handwheel elimination arrangement

ABSTRACT

A sewing machine is provided with means whereby the mechanisms thereof can be selectively operated in a normally forward direction or in a reverse direction such that the conventional handwheel on the sewing machine can be eliminated.

United States Patent ELIMINATION ARRANGEMENT Lawrence R. Goetz, Convent Station, NJ.

The Singer Company, New York, NY.

Filed: on. 13, 1972 App]. No.: 297,578

Inventor:

Assignee:

Field of Search 112/220, 219 R, 219 A, 112/210, 203, 221

References Cited UNITED STATES PATENTS 9/1972 Makihara et al 112/219 A Goetz Apr. 16, 1974 54] SEWING MACHINE HANDWHEEL 3,319,591 5/1967 Hamlett 112/220 3,363,594 1/1968 Kosrow 112/219 A Primary Examiner-41. Hampton Hunter Attorney, Agent, or FirmMarshall J. Breen; Chester A. Williams, Jr.; Martin Sachs [5 7] ABSTRACT 3 Claims, 3 Drawing Fig' ures' SEWING MACHINE HANDWI-IEEL ELIMINATION ARRANGEMENT BACKGROUND OF THE INVENTION The present invention relates to sewing machines, and in particular to the elimination of the conventional sewing machine handwheel without eliminating the ability of an operator to lower or raise the needle of the sewing machine. In the process of sewing various types of articles of clothing it becomes necessary to stop the sewing machine and change the orientation of the material without removing the needle from the work being sewn. Consequently, it is to the operators advantage to be able to maintain the sewing machine needle in the work piece-while changing the orientation of the work. It also is an advantage, under certain circumstances, to be able to raise the needle out of the work once the machine has stopped so that the work may be removed from the machine. In accordance with the principles of the present invention, the function of the handwheel, which conventionally permits the operator slowly to raise and lower the sewing machine needle is preferably accomplished with solid state control circuit arrangements.

SUMMARY OF THE INVENTION A sewing machine built in accordance with the principles of the present invention, has stitch forming instrumentalities and work feeding mechanism, a mainshaft operatively connected to the stitch forming instrumentalities and the work feeding mechanism, an electric motor connected to drive the main-shaft, first means effective to cause the main-shaft to drive the stitch-forming instrumentalities and work feeding mechanism in a normal forward direction, and second means effective to cause the main-shaft to drive the stitch-forming instrumentalities and work feeding mechanism in a reverse direction.

In accordance with the principles of the present invention, an improved sewing machine includes an operator-actuated speed controller connected to a drive motor and coupled to a source of AC power, a first means coupled to the speed controller for providing a relatively slow speed control, operator actuated switch means for-selecting either the speed controller or the first means while inactivating the speed controller, and a second means for reversing the sewing machine.

DESCRIPTION OF THE DRAWING FIG. 1 is a front view of a sewing machine in which the present invention is embodied;

FIG. 2 is a schematic circuit diagram of a handwheel elimination circuit arrangement according to the principles of the present invention; and

FIG. 3 is a schematic circuit diagram of an alternate embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and in particular to FIG. 1, wherein, is shown a sewing machine 10. The sewing machine 10, in which the present invention is incorporated, comprises a substantially rectangular hollow base 12 having it at upper side a work supporting surface or bed 14 including therein a throat plate 16. Suitably secured upon the hollow base 12 is a vertically disposed hollow standard 18 which carries an overhead bracket-arm 20 terminating in a hollow head 22 in which is mounted a reciprocatory needle bar 24 carrying needle 25. Also included in the hollow head 22 is a pressure bar 26 which is terminated in a presser foot 28. Additionally included in the sewing machine 10 is a loop taker 30, a thread tension control 32, a spindle 34 for retaining a spool of thread, and an elec trical drive motor 35 which is coupled, via a geared coupling means 37, to a drive shaft 39. All of the items mentioned above are found on a conventional sewing machine as well as stitch forming instrumentalities and work feeding mechanisms 43 as is well known in the art.

In a preferred embodiment, in accordance with the principles of they present invention, a single pole three position switch 36, and a double pole double throw switch 38 are provided on the standard 18 of the sewing machine 10. The function of the switches 36 and 38 will be described hereinafter.

The schematic circuit diagram of a preferred embodiment of the invention is shown in FIG. 2. The source of AC power, not shown, is coupled across terminals 40 and 42. A silicon controlled rectifier (SCR) 44 has its anode electrode 46 coupled to one side of the AC power source via terminal 40. The cathode electrode 48 of SCR 44 is coupled, via aserially connected armature winding 50 and a field winding 52 of a DC drive motor 35 and terminal 42, to the other side of the AC power source. The field winding has connected thereto a double pole double throw switch 38 in a manner adapted to reverse current flowing therethrough, as is well known in the art. A

A first voltage divider means, including a diode 54 which functions to reduce the power dissipated in the divider resistors, includes a resistor 56, a switch 36, a potentiometer 58 serially connected from one side of the AC source of power, via terminal 40, to the common connection 59 between the armature winding 50 and the field winding 52 of the DC drive motor 35.

A second voltage divider means includes a diode 54, a resistor 56, a switch 36, and a potentiometer 60 which is connected from one side of the AC source of power, via terminal 40, to the common connection 59 between the armature winding 50 and field winding 52.

The switch 36 in its first position completes the circuit between resistor 56 and resistor 58 thereby energizing the first voltage divider means and providing gating voltage, via diode 62, to the gate electrode 64 of SCR 44. The switch 36 by completing the circuit of the first voltage divider means opens or disconnects the second divider means.

The second position of switch 36 disconnects the first and second divider means turning off the SCR 44 and thereby the motor 35. A

The switch 36 in its third position completes the circuit of the second voltage divider means thereby providing a gating voltage, via diode 66, to the gate electrode 64 of SCR 44.

The diodes 62 and 66 function to electrically isolate the first and second divider means from each other. This permits different voltages to be coupled to the gate electrode 64 of SCR 44 which is dependent upon the position of switch 36.

It is to be noted that in accordance with the principles of the present invention, either the first voltage divider means or the second voltage divider means is energized at any one time.

Included between the gate electrode 64 and the cath ode electrode 48 of SCR 44 is a capacitor 68 which filters the DC voltage applied to the gate electrode 64 to insure proper firing of the SCR 44. A diode 70 is provided in parallel with capacitor 68. The diode protects the gate-cathode junction of SCR 44 from receiving damaging reverse voltages.

In operation, the switch 36 would normally be moved from the second position to its first position; as indicated in FIG. 2, energizing the first voltage divider means. The switch 38 in its first position provides current in the field winding 52 of motor 35 so that the motor will run in a forward direction. The resistance 58 is conventionally found in an operator-actuated footcontroller, not shown, associated with and coupled to the sewing machine 10. Depressing the foot controller causes the variable arm 72 of potentiometer 58 to move in a direction to increase the voltage applied to the gate electrode 64 of the SCR 44, thereby increasing the motor speed in a forward direction.

When an operator of the sewing machine releases the foot-controller the sewing machine randomly stops. In order to lower the sewing machine needle 25, and drive the machine in a forward direction, in accordance with the wishes of the operator, switch 36 is moved by the operator to its third position. The third position of switch 36 energizes the second voltage divider means and removes the energy from the first voltage divider means. In the preferred embodiment of the invention, resistor 60 is preset to provide a relatively slow movement of the needle bar 24 carrying needle 25. The switch 36 may be of a push button, slide, or toggle type, biased to the center (second position), thereby providing short or intermittent operation of the sewing machine motor when urged upwardly or downwardly by the operator and returning to the center or off position when released. Upon release of switch 36 the machine comes to rest at the position desired by the operator.

If the sewing machine operator desires to raise the needle bar, which has stopped in its lower most position, switch 38 is placed to its second position, thereby reversing the current flow through field winding 52. Moving switch 36 to its third position will thereby cause the motor 35 slowly to drive the sewing machine in a reverse direction raising the needle bar to the level desired by the operator. Referring now to FIG. 3, which is an alternate embodiment of the present invention, wherein like numerals refer to the like components. FIG. 3 is a schematic circuit diagram of the same circuit shown in FIG. 2, which incorporates principles of the present invention, and is modified to incorporate a four pole three position switch 74, which is biased to return to its central or normal position. Switch 74 in an alternate embodiment of the invention may be physically located in the same area as switch 38 in FIG. 1. Switch 74 has a central or normal position 76, a forward or upward position 78, and a reverse or downward position 80.

With switch 74 in an upward position the contacts 82 and 84; 86 and 88; 90 and 92; and 94 and 96 are shorted. When switch 74 in its normal position the contacts 84 and 98; 88 and 100; 92 and 102; and 96 and 104 are shorted. With switch 74 in its downward position the contacts 98 and 106; 100 and 108; 102 and 110; and 104 and 112 are shorted.

The operation of the circuit shown FIG. 3 is the same as that of FIG. 2. In the embodiment shown in FIG. 3 the sewing machine operator is required to move switch 74 in an upwardly direction to energize the second voltage divider means and reverse the current flow in field winding 52 thereby causing the motor to slowly drive the sewing machine in a reverse direction. The operator moving switch 74 in a downwardly direction causes the sewing machine to moving slowly in a forward direction.

As mentioned earlier switch 74, in an alternate embodiment of the invention, is biased toward its normal or central position 76 so that it will return to position 76 when released by the operator, thereby, energizing the first voltage divider means and causing the current to flow in a normal direction in the field winding 52 so that the motor will operate in a forward direction also. With the first voltage divider energized, the operator is able to control the speed of the sewing machine with the aid of the foot-controller in a normal manner.

Having thus set forth the nature of the invention, what is claimed herein is:

1. In a sewing machine having stitch forming instrumentalities and work feeding mechanism, a mainshaft operatively connected to said stitch forming instrumentalities and work feeding mechanism, an electric motor connected to drive said mainshaft, a main circuit for supplying electrical power to said electric motor and including an operator influenced speed control means, characterized by means substituted in place of the handwheel which is conventionally associated with a sewing machine mainshaft, said means comprising an auxiliary circuit for supplying electrical power to said electric motor and including a predetermined slow speed control means, operator accessible switch means for selectively connecting said electric motor to said main or to said auxiliary circuit and for influencing the internal wiring of said electric motor selectively to control the direction of electric motor rotation.

2. In a sewing machine as set forth in claim 1 in which said operator accessible switch means comprises a single three-position switch effective in the extreme positions to connect the auxiliary circuit to said electric motor and to effect a different direction of electric motor rotation in each extreme position.

3. In a sewing machine as set forth in claim 1 in which said main and auxiliary circuits are adapted to accommodate a source of alternating current electric power and the predetermined slow speed control means includes a silicon controlled rectifier. 

1. In a sewing machine having stitch forming instrumentalities and work feeding mechanism, a mainshaft operatively connected to said stitch forming instrumentalities and work feeding mechanism, an electric motor connected to drive said mainshaft, a main circuit for supplying electrical pOwer to said electric motor and including an operator influenced speed control means, characterized by means substituted in place of the handwheel which is conventionally associated with a sewing machine mainshaft, said means comprising an auxiliary circuit for supplying electrical power to said electric motor and including a predetermined slow speed control means, operator accessible switch means for selectively connecting said electric motor to said main or to said auxiliary circuit and for influencing the internal wiring of said electric motor selectively to control the direction of electric motor rotation.
 2. In a sewing machine as set forth in claim 1 in which said operator accessible switch means comprises a single three-position switch effective in the extreme positions to connect the auxiliary circuit to said electric motor and to effect a different direction of electric motor rotation in each extreme position.
 3. In a sewing machine as set forth in claim 1 in which said main and auxiliary circuits are adapted to accommodate a source of alternating current electric power and the predetermined slow speed control means includes a silicon controlled rectifier. 